1. Field of the Invention
The present invention relates to an information processing technique and in particular to a technique for performing a concerted operation between a central processing apparatus and peripheral apparatuses which constitute a computer system.
2. Description of the Related Art
The function of turning on/off, in a lump, the power supply of a server apparatus (i.e., a central processing apparatus) existing in an environment and the power supplies of a plurality of peripheral apparatuses (e.g., a disk array apparatus(es), a network relay device(s), a tape apparatus(es) and such) is increasingly important in terms of preventing mistakes in maintenance, such as forgetting to turn the power on or off, when carrying out maintenance in a large scale computer system environment. For that purpose, a server apparatus and individual peripheral apparatuses have conventionally been connected together by way of a network structured using a communication interface for use in a computer system such as a Remote Cabinet Interface (RCI), and by implementing the function of turning the power on/off of the entirety of apparatuses existing in the environment.
Incidentally, in a computer system storing a system volume (i.e., an operating system (OS) image) used for starting up a server apparatus in a disk array apparatus as one of the peripheral apparatuses, the disk array apparatus needs to be ready to be accessed at the start-up of the server apparatus. The above described power supply linkage function can certainly be implemented even in such an environment by utilizing the above described inter-apparatus network. In this case, however, there is a difference in the length of startup time between the server apparatus and disk array apparatus, and therefore it is necessary to wait for the other's startup time between the server apparatus and disk array apparatus.
One method of performing a waiting function at a server apparatus is a method of delaying the start of a booting process for a preset time period at all times after the completion of a power-on self test (POST) process. The following is a description of the method, referring to FIG. 1.
FIG. 1 shows how a process progresses when starting the above described computer system by using the above described method. Referring to FIG. 1, process (A) shows the progress of the process at the server apparatus, while process (B) shows the progress of the process at the disk array apparatus.
When turning on the power supply of the computer system in a lump, the power is turned on to the server apparatus in S1000 and, in concert with this, the power is also turned on to the disk array apparatus in S2000. This prompts the execution of an initialization process for the server apparatus to start in S1010 and, in parallel, the execution of an initialization process for the disk array apparatus to start in S2010.
Then, the execution of the initialization process is temporarily interrupted at the server apparatus and the starting of the disk array apparatus is delayed until the time t0. Meanwhile, the disk array apparatus completes the execution of the initialization process, shifts the process to S2020 and enters into a ready state (i.e., being ready to receive an access from the server apparatus), while the server apparatus interrupts the execution of the initialization process.
The server apparatus interrupts the execution only for a preset period of time, then completes the execution of the initialization process to shift the process to S1020 and starts the execution of a booting process. Then the server apparatus accesses the disk array apparatus for reading an OS in S1021 of the booting process. The disk array apparatus is already in a ready state at this time and therefore returns, to the server apparatus, a normal response to the access thereof and also sends the OS image in S2021.
The server apparatus reads the OS image sent from the disk array apparatus in S1022. When completing the reading, the server apparatus completes the execution of the booting process, shifts the process to S1030, and perform the startup process for the OS. This completes the series of steps of the startup process.
In the meantime, relating to the above described technique, Laid-Open Japanese Patent Application Publication No. Sho 64-44562 has disclosed a technique in which a service processor instructs a central processing apparatus to run an initiation program loading routine and then sets a certain period of time if the state of an input/output apparatus indicates a not-ready state and again instructs the central processing apparatus to run the initiation program loading routine if it is within the certain period of time.
The above described method for a server apparatus comprised in a computer system to wait for the startup of a disk array apparatus is faced with problems in terms of the following:
(1) A delay time is set under the assumption of a worst case scenario, and therefore a delay of a certain period of time always occurs even if the startup of the disk array apparatus is performed faster. For example, a disk array apparatus usually starts up in about five minutes; it may take about twenty minutes in the worst case if an error is detected in the initialization process.
(2) A server apparatus also needs a certain period of time at all times for detecting an error in a disk array apparatus.
(3) Since a server apparatus waits in the midst of an initialization process as described above, it needs to wait for a starting of work for a preset period of time even if only the maintenance (e.g., work to change setups of various parameters for a server apparatus) of a computer system is required after the completion of the initialization process for the server apparatus.
(4) If a computer system comprises a plurality of disk array apparatuses with the lengths of their startup times being respectively different, it is necessary to set the startup waiting time on the basis of the time required in the worst case.